The present invention generally relates to threaded insert insertion tools and, more particularly, to a threaded insert installation tool for areas with limited access and to a method for installing threaded inserts in areas with limited access.
Threaded inserts, such as Heli-Coil® inserts (Heli-Coil® is a registered trademark of Emhart® Teknologies), provide positive means for protecting and strengthening all tapped threads. Threaded inserts are typically precision-formed screw thread coils of stainless steel wire having a diamond shaped cross-section. When the treaded inserts are installed into tapped holes, the threaded inserts provide permanent 60-degree internal screw threads that accommodate any standard bolt or screw. The threaded insert is typically larger in diameter than the tapped hole. During installation of the threaded insert with an installation tool, the installation tool applies torque to the insert reducing the diameter of the leading coil allowing the leading coil to enter the tapped hole. After installation, the threaded insert expands outwards with a spring force that permanently anchors the insert in place. When installed, a threaded insert provides a precision female thread of high surface finish and strength. Threaded inserts may increase the thread life of a tapped hole, especially in materials having a low hardness, such as aluminum, by eliminating the erosion of the thread due to friction. Furthermore, threaded inserts may make a tapped hole stronger by distributing the load applied to the threads by an inserted fastener evenly to each coil. Threaded inserts are typically available in two designs, the standard insert, which has a free-running thread, and the screw-lock insert, which provides a locking torque on the mating fastener using chord on one or more coils of the insert. Threaded inserts were invented in the late 1930's to provide a solution for the repair of aircraft engines. Currently, threaded inserts are used in automotive, communication, aerospace, military and defense industries. Presently, in many applications, for example in the aircraft industry, threaded inserts are part of the original design to prevent the need to repair threads of a tapped hole. Furthermore, the use of threaded inserts yields a much stronger assembly than a tapped hole of the parent material, for example, aluminum, could provide.
Installation of threaded inserts may be achieved with a driving tang, which is removed after assembly. To permit the removal of the tang, a notch is cut into the section of a threaded insert to provide a shear point. The driving tang is engaged in an abutment or slot of an insertion tool and prewound into a nozzle. After placing the insertion tool over the correctly tapped hole, further winding will install the threaded insert to the correct depth. After withdrawal of the insertion tool, the tang needs to be removed to allow a fastener, such as a bolt or screw, to pass through the insert. Threaded inserts may be installed into a tapped hole using an appropriate hand or power insertion tool. Hand tools are typically designed with a threaded mandrel and a driving contour that allows the correct and efficient installation of the threaded insert. Hand tools may be operated with an offset handle. Power tools typically consist of the same front-end assembly as manual operated insertion tools, which include a prewinder, a mandrel and spacers, an adapter, and a reversible motor. Existing hand and power insertion tools for threaded inserts may not be operable in tight spaces or spaces with limited access. For some applications, for example, for insertion of threaded inserts in a space having an extended depth and a close proximity to surrounding walls, such as inside a cylinder or a barrel, prior art insertion tools may be impractical. It may be necessary to remove the offset handle from a prior art manually operated insertion tool and to use an additional tool, such as a wrench, to operate the front-end assembly of the insertion tool.
Prior art threaded insert insertion tools include, for example, U.S. Pat. No. 6,000,114 issued to Newton et al. The insertion tool disclosed by Newton et al. may be used for insertion of a tang-free threaded coil insert into a threaded opening. The prior art insertion tool includes a blade, which is formed with a drive hook. Although the prior art insertion tool enables the insertion of a threaded coil insert fully within a threaded opening of a support structure such that the trailing end of the insert is flush with the external surface of the support structure adjacent to the opening, the insertion tool may not be suitable for insertion of threaded inserts in tight spaces and in close proximity to walls of a cylindrical structure.
As can be seen, there is a need for an installation tool for a threaded insert that may be used in tight spaces and spaces with limited access. Furthermore, there is a need for an installation tool that enables the insertion of a threaded insert into a tapped hole inside a barrel that extends for a length and that has a relatively small diameter.
There has, therefore, arisen a need to provide an installation tool for threaded inserts that may be used in areas with limited access. There has further arisen a need to provide an installation tool that may be power operated in areas with limited access. There has still further arisen a need for a method to install threaded fasteners in tight spaces where the tapped hole may be positioned in close proximity to a wall and at an extended depth.